1. Field of the Invention
The present invention relates to a scanning endoscope that photographs and/or films an optical image of a front view of a subject that is circumferentially located around an insertion tube of the scanning endoscope.
2. Description of the Related Art
Japanese Patent No. 3943927 discloses a scanning endoscope which photographs and/or films an optical image of an observation area by scanning the observation area with light shined on a minute point in the area and successively capturing reflected light at the illuminated points. In a general scanning endoscope, light for illumination is transmitted through an optical fiber from a stationary incident end to a movable emission end and a scanning operation is carried out by successively moving the emission end of the optical fiber.
A general scanning endoscope is designed so that a field of vision of the scanning endoscope is in front of a distal end of an insertion tube of the scanning endoscope. However, it is difficult to observe certain types of subjects using such scanning endoscope. This is because it is difficult to adjust the position of the insertion tube in a thin lumen, such as a bronchial periphery, so that the distal end of the insertion tube faces the inner surface of the thin lumen. Accordingly, the inner surface of a thin lumen is photographed and/or filmed at a large angle of incidence with respect to the inner surface to be photographed and/or filmed. However, it is difficult to recognize the status of the inner surface by the image of the inner surface photographed and/or filmed from a large angle of incidence.